Cylinder liner having three-tiered surface finish
A cylinder assembly for use in an internal combustion engine is disclosed. The cylinder assembly may include a cylinder, a piston disposed within the cylinder, a plurality of piston rings encircling the piston, and a cylinder liner fitted around the piston in a cylindrical space in which the piston reciprocates. The piston may reciprocate within the cylinder along a longitudinal direction of the cylinder. The cylinder liner may include an upper section, a middle section, and a lower section. The upper section may be composed of a first texture; the middle section may be composed of a second texture that is rougher than the first texture; and the lower section may be composed of a third texture that is smoother than the first texture and the second texture.
1. A cylinder assembly, comprising:
a cylinder;
a piston disposed within the cylinder, and configured to reciprocate within the cylinder along a longitudinal direction of the cylinder;
a plurality of piston rings encircling the piston; and
a cylinder liner fitted around the piston in a cylindrical space in which the piston reciprocates, wherein:
the cylinder liner includes an upper section, a middle section, and a lower section;
the upper section is composed of a first texture, wherein the first texture is characterized by an oil retaining volume Vo of 0.05-0.30;
the middle section is composed of a second texture that is rougher than the first texture; and
the lower section is composed of a third texture that is smoother than the first texture and the second texture.
2. The cylinder assembly of claim 1 , wherein the first texture is characterized by an arithmetic mean roughness Ra of 15-35 micro-inches.
3. The cylinder assembly of claim 2 , wherein the second texture is characterized by an arithmetic mean roughness Ra of 35-55 micro-inches.
4. The cylinder assembly of claim 3 , wherein the third texture is characterized by an arithmetic mean roughness Ra of 15-25 micro-inches.
5. The cylinder assembly of claim 1 , wherein the second texture is characterized by an oil retaining volume Vo greater than 0.10.
6. The cylinder assembly of claim 5 , wherein the third texture is characterized by an oil retaining volume Vo of 0.05-0.10.
7. A method for producing a cylinder liner having an upper section, a middle section, and a
lower section, comprising:
hardening the upper section and the middle section;
rough honing the cylinder liner with a 150 grit super-abrasive at a speed of 250 RPM;
port relief honing the middle section with a 400 grit super-abrasive at a speed of 175 RPM;
finish honing the upper section with a 400 grit super-abrasive at a speed of 200 RPM; and
finish honing the lower section with a 400 grit super-abrasive at a speed of 200 RPM.
8. The method of claim 7 , wherein hardening the upper section and the middle section includes hardening until a hardness of at least a portion of the upper section and at least a portion of the middle section have a hardness greater than 50 on the Rockwell C scale.
9. The method of claim 7 , wherein port relief honing the middle section results in a crosshatch angle of 5-17°.
10. The method of claim 7 , wherein finish honing the upper section and the lower section results in a cross-hatch angle of 30-40°.
11. The method of claim 7 , wherein finish honing the upper section includes finish honing until a surface finish of the upper section has an arithmetic mean roughness Ra of 15-35 micro-inches.
12. The method of claim 11 , wherein port relief honing the middle section includes port relief honing until a surface finish of the middle section has an arithmetic mean roughness Ra of 35-55 micro-inches.
13. The method of claim 12 , wherein finish honing the lower section includes finish honing until a surface finish of the lower section has an arithmetic mean roughness Ra of 15-25 micro-inches.
14. The method of claim 7 , wherein finish honing the upper section includes finish honing until the upper section has an oil retaining volume Vo of 0.05-0.30.
15. The method of claim 14 , wherein port relief honing the middle section includes port relief honing until the middle section has an oil retaining volume Vo greater than 0.10.
16. The method of claim 15 , wherein finish honing the lower section includes finish honing until the lower section has an oil retaining volume Vo of 0.05-0.10.
17. The method of claim 7 , wherein rough honing the cylinder liner is performed for 2.5-3 minutes, port relief honing the middle section is performed for 2 minutes, finish honing the upper section is performed for 2.5-3 minutes, and finish honing the lower section is performed for 2.5-3 minutes.
18. The method of claim 7 , further including grinding the upper section and the middle section.
19. A cylinder liner comprising an upper section, a middle section, and a lower section, wherein:
the upper section is composed of a first texture, wherein the first texture is characterized by an oil retaining volume Vo of 0.05-0.30;
the middle section is composed of a second texture that is rougher than the first texture; and
the lower section is composed of a third texture that is smoother than the first texture and the second texture.